Voter surveys in the Mar. 6, 2012,
presidential primaries were conducted for the National Election Pool (The
Associated Press, ABC, CBS, CNN, FOX and NBC) by Edison Research. NEP members
prepared the questionnaires.

Election day surveys were conducted in the
following number of precincts per state:

State

# exit poll
precincts

# interviews

Georgia

30

1,833

Massachusetts

25

1,546

Ohio

40

2,728

Oklahoma

20

1,097

Tennessee

30

2,530

Vermont

20

1,109

Virginia

20

1,044

The polling places are a stratified
probability sample of each state, factoring in size and past voting history.
The sample is designed so that everyone who voted in the state's primaries
Tuesday has a known probability of being included.

At each sampling location an interviewer
approached voters at a specified interval -- for example, every fifth voter
-- as he or she exited the polling place. The interval helps ensure the
randomness of the sample. In states where both Democrats and Republicans held
primaries, voters were asked which primary they had just voted in and were
given a paper questionnaire specific to that primary.

In Ohio and Tennessee -- states with
expected high incidence of absentee or early voting -- telephone polls also
were conducted from Feb. 27 - Mar. 4, screening for people who had already
voted or said they were certain to vote before Tuesday. Results from the
telephone interviews were blended into the election day samples, weighted to
the estimated proportion of early voting among the overall electorate. These
surveys included 410 voters in Ohio and 640 in Tennessee.

All samples are approximations. A measure
of the approximation is called the sampling error. Sampling error is affected
by the design of the sample, the characteristic being measured and the number
of people who have the characteristic. If a characteristic is found in
roughly the same proportions in all precincts ("non-clustered") the
sampling error will be lower. If the characteristic is concentrated in a few
precincts the sampling error will be larger. Gender would be a good example
of a characteristic with a lower sampling error. Characteristics for minority
racial groups will have larger sampling errors.

For these polls, the margin of sampling
error for results based on the full sample was plus or minus 4 percentage
points in Georgia, Massachusetts, Oklahoma, Vermont and Virginia, and plus or
minus 3 percentage points in Ohio and Tennessee.

The table below lists typical sampling
errors for this exit poll for non-clustered characteristics at the 95 percent
confidence interval. No more than one time in 20 should chance variations in
the sample cause the results to vary by more than this amount for
non-clustered characteristics. However, non-sampling
factors such as question wording and order and voter non-response may
increase total error.